Door and latching



Sept.' 17.,l 1963 R. L. DUGGER DOOR AND LATCHING 5 Sheets-Sheet 1 Original Filed Dec. 29, 1955 INVENTOR.

Sept. 17, 1963 R. l.. DUGGER 3,103,995

DOOR AND LATCHING Original Filed Deo. 29, 1955 5 Sheets-Sheet 2 L .F.Z'EZ E w* E FIC-:115'

98 INVENTOR. Tg2? gu .K

Mum l a1/fuma Sept. 17, 1963 R. L. DUGGER 3,103,995

DOOR` AND LATCHING Original Filed Dec. 29, 1955 5 Sheets-Sheet 3 fm LJ //////////,//////W/ i I I' l l' SMHII #fram/frs m 1N VEN TOR. I\| lli Sept. 17, 1963 R. L. DUGGER DooR AND LATCHING 5 Sheets-Sheet 4 Original Filed Deo. 29, 1955 New Sept. 17, 1963 R. l.. DUGGER DoQR AND LATCHING 5 Sheets-Sheet 5 Original Filed Dec. 29, 1955 Alina United States PatentOii ice 3,103,995 Patented Sept. 17, 1963 3,103,995 DOR AND LATCHING Ralph I... Dugger, Rte. 1, Hopkins, Minn. @riginal application Dec. 29, 1955, Ser. No. 556,198. Divided and this application Apr. '7, 1960, Ser. No. 20,734

Claims. (Cl. 189-46) This application is a division of lmy application, Ser. No. 556,198, tiled December 29, 1955, now abandoned, which is in turn a continuation-in-part of my application, Serial No. 454,365, iiled September 9, 1954, now Patent No. 2,937,415, issued May 24, 1960, both of which applications are incorporated herein by reference.

rIhis invention relates to large door latching mechanisms where it is desired to provide a large door which can be quickly opened and closed and securely latched.

It is an object of the invention to provide improved latching apparatus for a widespand overhead door, together with improved operating mechanism for releasing the door from all of its latches simultaneously across its entire width.

`It is another object of the invention to provide latching mechanism for large doors which accommodates movement of the door span truss relative to the door.

`Other and further objects are those inherent in the invention herein illustrated, described, and claimed, and will be apparent as the description proceeds.

To the accomplishment of the foregoing and related ends, this invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principles of the invention may be employed.

`'Ille invention is illustrated with reference to the drawings in which corresponding numerals refer to the same parts, and in which:

FIGURE 1 is a front elevational View of a portion of a building having a door opening closed by a door fabricated according to the present invention;

FIGURE 2 is a vertical sectional view taken along the line and in the `direction of arrows 2 2 of FIGURE l illustrating a section through the door and portion of the building when the door is in closed position and illustrating the rigging by which it is supported and manipulated;

FIGURE 3 is a sectional view taken in the direction of arrows 3 3 of FIGURES 2 and 5 and shows the rear or interior side of the door in rear elevation;

FIGURE 4 is a horizontal sectional view through the door at one of its side jambs at the level ,and in the direction of arrows 4 4 of FIGURE 3. This view Iis enlarged as compared to FIGURE 3;

FIGURE 5 is a horizontal sectional view entered through the building and door. This view is tak-en at the level of line 5 5 of FIGURE 2, which latter however shows a vertical section only half way through the buildme;

FIGURES 6, 7 and 8 are enlarged fragmentary vertical sectional views through the door. FIGURE 6 shows the head of the door, its overhead support, and some of the latching details and one mode o-f hashing;

FIGURE 7 is another view corresponding to FIGURE 6, but illustrating another mode of flashing;

IFIGURE 8 is a section at a lower level illustrating the cable support attachment;

FIGURE 9 is a related fragmentary front elevational View taken in the direction of arrows 9 9 of FIGURE 8. FIGURES 8 and 9 together show the mode of cableend anchorage to the door;

FIGURES 10 and 11 illustrate the latching. FIGURE l0 shows a horizontal view at the level lit-L0 of FIG- URE 7 of one latch; FIGURE l1 is an enlarged vertical sectional view taken in the direction of arrows 11-11 of FIGURE 10;

FIGURES 12 and 13 relate to FIGURE 2 and are somewhat enlarged views of the crank mechanism by which the door is operated, FIGURE 12 being a vertical elevational view in the direction of arrows 12,-12 of FIGURE 2, and FIGURE 13 is a side elevational View in the direction of arrows 13 13 of FIGURE 12.

Referring to the drawings, the front elevation of the door and the adjacent portions of the building is illustrated in FIGURE 1 and as there shown, the door consists of a unitary flat panel having a width W and a height H for closing the door opening O. While the door may be used in any building for which it is adapted. it is here illustrated as applied to a multiple nested-T hangar.

As will be observed from FIGURES 2 and 5, and without limitation on the invention, the illustrated building has a building centerline CL extending throughout r'tne length of the building.

As shown in FIGURE 5 there is a hanger unit U1 partially illustrated and adjacent and nested with it is the hangar unit U2, having a hangar unit center line transverse to the building centerline. Hanger unit U2 is shown in complete plan and is nested to a third hangar unit U3, partially illustrated.

As shown for hangar unit U2, each hangar unit has a tailbay of rectangular area which for unit U2 is bounded by a tailbay backwall 19, this being also one portion of the building sidewall, and by Walls 2 and 3 and the building centerline. The wingbay space is entirely open across the front from the co-rner of walls 1 and 17 to the corner of walls 4 and 18, and is closed by the hangar door.

As illustrated in FIGURE 5, the hangar units are sized dirnensionally ofV multiples of the modular dimension, viz: MODl, MO'DZ, MODS, and M0134. A truss is provided at S along the centerline of the building over each tailbay TB, and another truss 9 is provided over each hangar unit door opening.

The particular build-ing here described is merely illustr-ative of one kind of building for which the overhead doors are adapted..

From FIGURE l it will be observed that the truss 9 is covered on its front surface by a sheeting 10. In FIG- URE 2 the bottom cord of the door truss is shown as composed of a pair of angles 11 and the top cord as a pair of angles 12. The truss includes as `a part of the .truss structure parallel vertical members 13 in 4spaced apart relation, as shown in FIGURES 3 and 5, which serve 'as mountings for the front end of the door supporting tracks, as wil-l be described hereinafter.

For attaching` the wood sheeting on the front of the ,truss there -is provided a wood nailer 14 along the bottom cord of the truss, the nailer being held in place by bolts 15, another nailer 14A being provided above the roof joists Rl level with the roof decking RD.

Referring to FIGURES 1 and 5 it will be noted that the width W of the door spans the entire door opening O, except for a small clearance space SC at each side. When the door is opened the entire door opening O (which is the dimension W plus the clearance space SC at each end), .is entirely open and is available for movement therethrough of any wide olbject such as the wing of an airplane.

In FIGURE *1, the door is illustrated as of fa height H. A small bottom `clearance BC is provided. At the top of the door a clearance space is provided as shown :at TC in FIGURE 6.

According to the present invention, the entire door width W and height I-I is one unit composed of panels P1, P2, P3, and P4, such panels being set side-to-side and so composed and joined as to form` a unitary door area. Thus referring to FIGURE l, one panel may 'be considered as extending throughout the width P1 from one side edge 21 of the door to the dotted line 22. The next panel P2 extends from line 22 to line 23; the third panel eX- tends from the line 23 to line 24, and the fourth panel extending from line Z4 to the `opposite side edge Z5 of the door.

For cach of the panels P1 through P4, or as many as may be used, there 4is a backbone support provided along the vertical centerline of the panel. In the illustrated embodiment of the invention, such support or backbone of each panel is composed of a pair of structural angles. Thus referring to FIGURE 3, which shows the interior view of the door, such vertical backbone support for panel P1 is composed of the angles 27 and 28. Similarly the vertical backbone support of panel P2 is composed of the angles 29 and 30; the vertical backbone support of panel P3 `is composed of the backbone 31 and 32 and the backbone support of the panel P4 is composed of the angles 33 and 34.

The purlins are set at intervals horizontally in spaced relation in respect to the door height. Two such purlin stiffeners are provided at 36 and 37, at a horizontal level, part way up the door, which it is desired to guide along a predetermined calculated path, either arcuate or straight, as described in my application aforementioned.

Latches are provided as will be described adjacent each of 4the backbones and either curbs SI-SI shown in dotted lines in FIGURES 2 and 3, or blocks are set a rlittle above door level, adjacent the bottom of the backbones or along lower purlin 35. The backbones and hence the door are thus held securely at the top and bottom.

Referring to FIGURES 2, 3, 4, 6, and 8, it will be observed that the angles composing the backbone are set so that adjacent anges of the angles are parallel in closely spaced relation, as shown in FIGURE 4. This presents the cooperating llanges of the angles in a common vertical plane directed to the front of the door and parallel with the plane of the door. Across the front of these angles are then provided a plurality of clips 41, 42, 43, 44, and 45, sce FIGURES 2, 6, and 8. Each clip has an inner plate 42A (see FIGURE 3) which is yof a thickness equal to the metal forming the ange of the purlin which is received in the clip. Then in addition, there is another plate 42B of the clip which serves to lap upwardly over the ange of the purlin. with the angles forming the backbone stiieners (as angles 27-28) and are then welded in place across the angles of the backbone as shown for angles 27 and 28 for FIGURE 4. The clips thus hold the backbone angles in pre-assembled relationship and hold the purlins.

Between the purlins 36 and 37 there is a forwardly extending bar 44 at each backbone support. This bar 44 lits into the space between the backbone angles as shown in FIGURE 4 and is welded thereto. This bar 44 extends outwardly between the yangles and continues outwardly through the width .dimension of the purlin and then still farther throughout the thickness dimension of the sheeting S. The bar 44 sticks out `a little and is an anchorage for the cable supports, the stresses being carried back to the backbone angles.

The sheeting of the door, here illustrated as steel roof decking S, see FIGURES l, 2, 4, and 6, is nailed or otherwise fastened to the purlins 3S through 39.

Referring to FIGURE 7 it will be noted that the portion 49B of the sheeting 49 is illustrated as extending inwardly with respect to the door and into contact with the front surfaces of the backbone angles 27-23 where the sheeting rises vertically at 49D, to a height sufficient so that it is above the inner edge of `the yinner angle 11 forming the bottom cord of the truss. This flange 49B The clips `are pre-assembled p thus closes firmly against the inner edge of the bottom chord of the truss and effects a tight closure thereagainst. The flange 49D is notched appropriately as shown to clear the latches of the door, which will `be mentioned hereinafter. FIGURES 6 and 7 thus illustrate two modes of construction of the top sheeting metal 49 of the door by which varying closures may be made.

As shown in FIGURE 3, diagonal cross bracing 50--50 is provided between the backbone angles 27-28 and the backbone angles 29-30 and is provided between the backbone angles 31-32 and 33-34. z

`The sheeting S has great stiffness about bending along a horizontal line with reference to the door. Thus the sheeting resists bending about the purlins and when a wind load is exerted against the exterior surface of the door the load is accordingly transferred to the purlins and from the purlins to each of the backbone angles of the door and thence to the latching members generally designated 121-124 and 151-154 at spaced intervals across the head of the door and to curbs or stops at floor level.

Each of the panels P1 through P4, or as many as are used, are individually suported in an identical manner. The individual supports for panel P1 will be described and in will be understood that the supports for panels P2 through P4, or as many as are used, will be identical unless otherwise stated. Thus referring to FIGURES l, 2, 3, 4, and 5, the supporting structure for the door comprises in each instance a cable which is fastened to the outer surface of the door midway between the top and the middle thereof, and an overhead track. Referring rst to the cable structures, as previously described, each of the pairs of backbone angles, as for example, the backbone angles 27-28 for panel P1, has an outwardly extending plate 59 fastened in the space between adjacent flanges of the angles 27-28 and extending out between the pairs of purlins 36 and 37 and through a slot, which is cut in the sheeting S, and extends slightly beyond the front surface of that sheeting. On the extending end of member 59 there is a pivot hole to which a cable clevis 58 is attached. This construction and the clevis are best illustrated in FIGURES 2, 8, and 9.

An effective and economical form of cable clevis 58 is illustrated. A standard steel cable thimble 63, galvanized or otherwise rustproofed is spread sufficiently so as to be snapped over the bar 62, and a stranded steel cable likewise of galvanized stock 64 is then wrapped around the thimble 62 and is securely fastened in place by aircraft type squeeze fasteners 65. The cable 64 then runs directly upwardly in front of the sheeting S1 of the door parallel thereto and then passes over a pulley 65 and runs substantially directly inwardly into the building along the path 64A, see FIGURE 5.

The level at which the plates 5.9 are inserted through the door, and hence to which the cable 64 is attached, are identical for each of the panels P1 through P4 served by the cable supports.

Reference is now made to the track structure 68 serving the panel P1. Such track structure 68 is identical with all of the remaining track structures serving the panels P2 through P4 and hence only one need be described. The track structure 68 comprises a track 69 which is securely fastened Ito a structural steel member 70. At the front end of the track assembly there are a pair of spaced vertically extending plates 71 having a secure fastening plate 72 welded between their upper ends. The plates 71 thus extending upwardly are apertured at 73 to receive a pivot pin 74 upon which the pulley 65 is journalled. An arcuate portion of the pulley 65 extends outwardly through the sheeting 10 so as to permit the pulley to receive the upward run of cable 64. After passing onequarter of the way around the pulley 65 the cable continues along Ithe portion 64A of its run as will be described.

Referring to FIGURE 6 particularly, it will be observed that the web tifi of the structural T 7G is cut away along the line 70B so as to provide adequate clearance for the lower circumferential portion of the pulley 65. The plates 71 are joined together at their upper edges by the cross-plate 72, welded securely in place, and the plate 72 is apertured to receive a long bolt 75 the head of which is situated below the plate 72 and the shank of the bolt extending upwardly. The structural members 13-13 which are made a part of the truss, and are illustrated in FIGURE 3 have welded to them a cross bracket 76 which is likewise apertured in proper position to receive the upward shank of the bolt 75. Above the plate 76, there is a spring 77 around the bolt. The lower end of spring 77 bottoms securely upon the plate 76. A washer and nut are placed at 78 on the bolt and are screwed down as to compress the spring 77 which accordingly supports the bolt 75, and through it supports the front end of the entire track structure 68.

Movement of the track structure 68 toward and away from sheeting is precluded by a pair of clips 79--79 which are welded to one of the side plates 71 and spaced so as to bear, with slight clearance, against the adjacent edges of one of the vertical angles 13. The rear end of the track structure 68 is supported in any sui-table manner from the overhead framing of the building, here illustrated as a hanger 16 which goes through an aperture 17 in the rear end of the track structure 68 and is hooked on to the -bar joist RI.

In the Itrack 69 of the track structure 68, there is positioned a roller hanger, generally designated 80, of ordinary commercial design, as is the track 69. The hanger has a` downwardly extending pendant 81 which is apertured at its lower end to receive a pivot pin 82 which passes through suitably placed apertures in the upper end ofthe backbone angles 27 and 28.

Referring to FIGURES l, 2, 3, and 5 and 6, particularly, it will be noted that the run 64A of the cable 64 extends substantially straight inwardly Within the building with respect to the sheeting 10. It continues this run, designated 64A, and thence passes around pulley 83 which is disposed in a substantially horizontal plane and thence passes directly over a drum 84, which is sufficiently wide to receive the corresponding runs of the remaining pulley as will be described. The run 64A of the cable is preferably displaced slightly so as to avoid the rear hanger 16 by which the track lis supported.

The corresponding cables for the panel P2 through P4 are similarly `attached to backbones 29-30 31-32 and 33-341 Each of these cables is set to run over a pulley disposed in la horizontal plane as at 88, 39, and 90. These pulleys are displaced sidely lvertically with reference to pulley 83 as follows: The pulley 90 is set the lowest, the pulley 39 slightly above it so as to clear the run 37B of the cable 87. The pulley 88 is set stiil a little higher so as to clear the runs 86B and 87B of the 'cables below it, and the pulley 83 is set still a litt-le higher so that Iit is disposed over the cables 86B, 87B and 85B and will cause no interference. Only a slight displacement vertically is necessary since the cables are of small diameter. The bracketing for the pulleys 88, 89, and 90 is varied, as permitted by the buildin-g structure.

The drum 84 is carried on shaft 84A which is journalled in bearings 91-91 mounted on a heavy frame- Work 92 that is fastened in any suitable manner to the adjacent walls d and 6. This frame 92 may serve as the mounting for the bracketing of pulley 83. The drum 84 is of suflicient Width so as to permit the runs 64B, 85B, 86B and 87B of the several cables to pass thereover. The cables then extend directly downwardly as shown in FIGURE 2 along the runs 64C, 85C, 86C and 87C, and are fastened to the supporting framework of the weight box generally designated 92.

In each of the runs of the four cabfles here illustrated, or as many as are used, there is provided a turnbuckle, as illustrated at 64D in FIGURE 2.

Referring to FIGURES 2, 12 and 13, the drum 84 is carried by and lwelded to a shaft 84A which turns in heavy bearings 91, and at the outer end of the shaft there is provided a chain sprocket 94 over which runs a roller chain extending downwardly. A sheet metal shield, generally designated 96, is provided 'around the Yweight box 92, the shield being composed of frameworks 96A-96A that are fastened in `any suitable manner -to the adjacent walls 4 and 6. Upon the frameworks 96A there is the shield and also mounted a piate 98, having slots 98A which t over, outwardly extending screws 99 of the framework pieces 96A, see FIGURE 12. Nuts placed on these screws will hold the plate 98 in any position of adjustment within the limits of the slots 98A. The plate 98 is provided with an internal stiften/er 100 and a stub shaft 101 which extends outwardly and is provided with 'a spacing collar at 102. A sprocket at 103 on sha-ft 101 is turned by a crank handle 104, having `a hand piece 105 solidly welded to the sprocket. The entire sprocket 1013 and crank 104 assembly is held in place by a collar l106 on the router end of the stulb shaft 101. The chain 95 runs over the sprocket 103 and hence,` as the crank 10d- 105 is turned, it will rotate the drum 04 and hence impart movement to the several cables where they run over this drum.

On the inside of thedoor, `at each end of the pnrlins 36' and 37, there are provided knuckle joints generally designated 106 and 107. These may conveniently be made by providing a pair of vertically extending angles 10S-103 and 10Q-109, which are spaced apart and wel-ded to the ends of the purlins 36 and 37 `as shown in FIGURES 3 land 4. Notches are provided in the outwardly extending flan-ges of the angles 108 and 109 and a bar `110 is laid in the notches and welded. A similar bar 111, is provided for the angles 109. This bar serves as a. tnunnion on which a piece ot pipe 112 for the bar 110 and 113 for the bar 111 is journalled. To this short length of pipe 112 or 113 Athere is welded the end of an inwardly extending radius rod 114 at the right end and 115 for the left end as shown in FIGURES 3 and 5. These radius rods extend inwardly and upwardly as shown in FIGURE 2 and fat their inner ends are provided with a pivot as at 114A in FIGURE 2 which turns upon a pivot 116 set in the wall 4 and the pivot 115A which turns upon -a pivot 117 set in the wall 1.

When the door is up, the entire area is open from the inner surface :of wail 1 to the inner surface of wall 4,l vbeing without jambs or other obstructions which consume such valuable doo-r opening space. I prefer this form of construction, but if desired the knuckles 110 and 111 may be extended over the edge of the door and provided with rollers run in tracks suitably spaced.

For holding the top or head of the door against inward deflection when in the vertical (closed) position, I provide a plurality of =latching bolts 121-124 and cooperating llatch mechanisms generally designated 251-254, best illustrated in FIGURES 2, 3, 5, 6, 7, 10 and l1. The cooperating latching bolts 121-124 and latch mechanisms 251-254 are here illustrated as being one cooperating pair (bolt `and latch mechanism) `for each of the pairs of backbone structures 27-28 through 33-34. If desire-d, however, a cooperating bolt and latch mechanism may be provided on each side of each backbone or in other locations along the head of the door. The bolts 121-124 `are heavy, flat bar stock and extend :downwardly and are provided at their inner face with a small piece lof pipe, welded on it as |at 126, see FIGURE 6. The trunnion pipe receives a pivot pin 127 which extends through similar short lengths of pipe which are slipped on the ends of the .pin land welded to a main horizontal pivot pipe 128. The pipe 128 extends across from the backbone angle 27-28,`thence across three of the vspans between adjacent backbone structures andvbeyond the backbone structure 33-34. The pivot pipe 128 -is suitably journalled in any form of journal on the front surfaces of the an'ges of the angles comprising each backbone structure, so as to be in the space occupied by the purlins as best illustrated in FIGURE 6. At one end the -pipe 128 is provided with weld-o-n handle 129 which is normally pulled upwardly by a spring 130 attached to a hook 131 at an upper part of the backbone structure. The handle 29 is also provided with a pull rope 132 which extends downwardly and is hooked at 133 to some convenient location Iat 'a ylower portion of the backbone structure. By pulling on the rope, the pipe 123 may be rotated through approximately l2() degrees and when it Iis released, the spring 130 will fetch the handle 129 up and hence rotate the pipe 128 in a reverse direction. This movement is communicated to each of the bolts 121-124 for moving them up and down. This construction is similar to the construction of the bolts, and their mountings and controls illustrated in my application aforementioned. The upper portions of each of the bolts 121-124 `as stabilized vagainst inward movement by a small clip as at 121A for the bolt 121. These yclips may be simply a short bar of steel held on lany suitable spacers welded to the top channel 40 as shown in FIGURE 6. The clips are made so as to provide a rather loose lit, as close tolerance is not required.

It is a feature of the present invention that the upper ends of the bolts are held by latches 251-254 of improved form, which are unaffected in their operation by vertical movement of the latch with reference to the position of the upper end of the bolt. In very long span trusses, some vertical movement of the truss, and hence everything attached to it, is occasioned by loading of the roof due to snow or other variable loading and due to temperature changes, and vertical movement of upwards to one inch must sometimes be tolerated on truss spans of great lengths. It is a feature of the present invention that the latching mechanism is of such design as to tolerate such variations without malfunctioning. rllhe latching mechanisms 251-254 are identical and hence only one will be specifically described. They are best illustrated in FIGURES l and 11. The latch mechanisms 251-254, of which 251 will now be described, consist of a pair of frame plates 225 and 226 which are pre-assembled and held together by a cross frame plate 227 welded to the rearwardly extending portions of the plates 22S-226. It will be noted that each of the plates 225 and 226 is rectangular except that it is cut off along the front edges 225A and 226A so as to avoid interference with the movement of the upper end of the bolts when the door is closing. In FIGURE 10, the bolt 121 is shown in the full lines -in the door-closed position, but the position 121B is the position of the bolt when the door is approaching closed position and 121C shows Vthe position of the bolt after it has entered the latch and is beginning to be latched and the full line position shows the finally latched position. On each one of the plates 225 and 226 there is an upwardly extending pin as at 228 for the plate 225 and 229 for the plate 226. Each `of these pins is provided at its upper ends with a slot,

as 228A and 229A and above the bottom of the slot the pin is provided with a drilled hole as at 228B, FIGURE 11, through which the split key 230 and 231 for the two pins 228 .and 229 respectively may be inserted. The pins are placed through the plates 22S-226 and are welded at the underside as at 223C, FIGURE *11. Before welding in place, the position of the slot 228A is oriented so that a coil spring, when placed thereon, will have proper tension as will be described. Upon each of the pins 228 and 229, there is placed a latch member as 232 for the pin 228 and 233 for the pin 229. These latch members are of bar stock and are provided with a central aperture so as to swing on the pin 228i. FI`he aperture is approximately in the middle so that the center Aof moments of the element 228 (or 229) around the i pivot pin comes at approximately the aperture on which it pivots. A stop, as at 234 for the latch 232 is provided and a similar stop 235 is provided for the latch member 233. The inner ends of the latches are curved off as at 232A for the latch `232. The radius of this curvature is such that the latch as it swings around its pivot will not present any surface which extends much beyond a certain line across the mechanism, here illustrated as the line 23S-238. This line is the intersection of the end surface 232A of the latch 232 and the end surface 233A of the latch 233 as they pivot and of the edge planes of the rectangle representing the cross section of bolt 121. The line 238` is so located when the latch mechanism is welded in place on the truss, so as to allow a clearance LC which is slightly more than the thickness of the bolt 121. It will be observed that the bolt, when the door is closed, will close against the inner edge 11A of the inner angle 11 of the bottom cord of the truss. This may or may not coincide with the inner edge 227A of the bar 227 which is merely provided to hold two pieces, 225-226 together during manufacture. However, the distance LC, see FIGURE 10, is slightly thicker than -the bolt 121. Thus, where the bolt stock 121 is onehalf inch in thickness, I prefer to have a dimension of 5/3 to 3%; of an inch at LC. Each of the latch elements 232 and 233 is provided with a small clip as at 240 for the latch element 232 and 241 for the latch element 233. These clips receive the outwardly extending ends of the spring members .242 and 243 respectively. Thus a coil spring is provided as illustrated at 242 for the latch element 232. and at 243 for the latch element 233. Referring to FIGURE 1l, the spring 242 is wound so as to have a cross key portion 242A which, when on the pivot shaft 228, will reside in the slot 228A where it is held by the split key 230. The spring then coils in a clockwise direction as shown in kFIGURE l0 and terminates along a straight run at 242B which extends under the clip member 240 and is held. The tension of the spring is such that it tends to move counterclockwise, in the direction of arrow 244 and thus tends to move the latch element 232 in such counterclockwise direction, see FIG- URE 10. The spring 243, is wound so as to have an opposite movement and tends to move its latch element 233 in a clockwise direction as shown by the arrow 245. The latch elements 232 and 233 normally stop as shown in FIGURE l() against stops 234 and 235 respectively. The position of the pivot shafts 228 and 229 is adjusted before being welded in so that the springs will have appropriate tension. The movement of the latches 232 and 233 is, of course, limited by the stops 234 and 235 respectively. When the operator desires to close the door, the crank 104-1tl5 is turned in an appropriate direction so as to lift the weight box. The door will then move from an open position toward the closed position. Meanwhile the spring has pulled the lever 129 upwardly and hence all of the bolts 121-124 are pulled to an upward position such that their upper ends are a slight distance above the upper surfaces of the latch elements 232 and 233.

Referring to FIGURE l0, as the door is being closed, the bolt 121 moves (and all similar bolts 122-124) successively through the positions 121B and 121C, shown in dotted lines. "In so doing, the adjacent edges of the latch elements 232 and 233 form a soit of V-shaped guide which guides the upper end of the bolt 121 in between them regardless of the sideways position of such bolt. The bolt does not snag upon the plates 225-226 since they are cut back along the lines 225A and 226A respectively inwardly in respect to the facing edges of the latch elements 232 and 233. As the bolt moves inwardly, it finally engages the adjacent edges of the latch elements 232 and 233 and begins to spread them apart, and as it intersects the inner edge of the latch the curved portions 232A and 233A of the latch elements respectively will snap in behind the bolt and the door will thus necessary for the bolt to move inwardly beyond its final latched position in order to obtain the latching condition. In other words, as soon as the bolt passes the intersection of the curved surface 232A and the adjacent surface of the latch 232, and corresponding intersections for the latch 233, the entire latch element may snap back to the locked position shown in FIGURE and from then on the Abolt is securely held.

When the truss moves up and down due to inherent deection, the latching elements still hold the bolts securely in place. When it is desired to release the door, the handle 129 is pulled down by means of the rope 132 and this pulls down all of the latch bolts simultaneously to a position such that they clear the lower surfaces ot the plates 225 and 226. Then by continuing a steady pull on the rope 132, the head of the door is moved inwardly to a position clear of the latching mechanism where it will stay while the operator goes to the operating mechanism at the weight box and turns the crank 104-105 to complete the opening of the door.

As many apparently widely `different embodiments of this invention may be made without departing from the spirit and scope thereof, it is therefore to be understood that I do not limit myself to the specilic embodiments herein.

What I claim is:

1. In a planar door for closing an opening beneath an overhead structural support, said door having a head edge and a means for supporting it for closing movement from a generally horizontal plane in which the door is elevated and open to a generally lower position in which the door is vertical and closed, said head edge being translated toward said overhead structure during such closure movement, a plurality of spaced latch bolts secured to the door `and extending vertically above the head of the door and means on the door interconnecting the spaced bolts for simultaneously retracting them toward said edge, and a plurality of spring biased latch elements mounted on said overhead structure laligned with said latch bolts for movement to a latching position in which they laterally engage `and positively hold the. bolts, said latch elements being engageable by said bolts for holding said bolts as the door is closed, said bolts being disengaged from said latch elements when said latch elements are in latching position by retracting the bolts toward the door head edge.

2. The combination lof claim 1 further characterized in that the latch elements are mounted for movement in a latch element plane generally normal to and above the door head edge which latch element plane is intersected by the ends of the bolts sweeping through arcuate movement as the door is closed.

3. The door of claim 1 further characterized in that each latch element is carried on a latch element frame which, as an entity, is attachable to the overhead structura-l support.

4. The door of claim 1 `further characterized in that for each bolt there are provided a pair of latch elements mounted on the overhead structural support for separately engaging opposite lateral surfaces of said bolts.

5. The door of claim l further characterized in that for each bolt there is provided a separate latch element frame having a slot extending along 'the line of movernent that the latch bolt moves as the door is closed, said latch element frame being mounted on the overhead structure in a position such that the bolt will enter the slot as the door closes, said latch element being mounted on the latch element frame so `as to be swung from the.

path of movement of the bolt in the slot and then return behind the bolt as the door closes, for holding the bolt from reverse movement out ofthe slot.

References Cited in the lle of this patent UNITED STATES PATENTS 357,943 Stamm Feb. 15, 1887 1,053,124 Ekberg Feb. 11, 1913- 1,812,411 Norton lune 30, 1931 1,955,525 Bales Apr. 17, 1934 2,023,193 Byrne Dec. 3, 1935 2,163,394 Clark June 20, 1939 2,286,082 Goodman June 9, 1942 2,793,891 Frye May 28, 1957 

1. IN A PLANAR DOOR FOR CLOSING AN OPENING BENEATH AN OVERHEAD STRUCTURAL SUPPORT, SAID DOOR HAVING A HEAD EDGE AND A MEANS FOR SUPPORTING IT FOR CLOSING MOVEMENT FROM A GENERALLY HORIZONTAL PLANE IN WHICH THE DOOR IS ELEVATED AND OPEN TO A GENERALLY LOWER POSITION IN WHICH THE DOOR IS VERTICAL AND CLOSED, SAID HEAD EDGE BEING TRANSLATED TOWARD SAID OVERHEAD STRUCTURE DURING SUCH CLOSURE MOVEMENT, A PLURALITY OF SPACED LATCH BOLTS SECURED TO THE DOOR AND EXTENDING VERTICALLY ABOVE THE HEAD OF THE DOOR AND MEANS ON THE DOOR INTERCONNECTING THE SPACED BOLTS FOR SIMULTANEOUSLY RETRACTING THEM TOWARD SAID EDGE, AND A PLURALITY OF SPRING BIASED LATCH ELEMENTS MOUNTED ON SAID OVERHEAD STRUCTURE ALIGNED WITH SAID LATCH BOLTS FOR MOVEMENT TO A LATCHING POSITION IN WHICH THEY LATERALLY ENGAGE AND POSITIVELY HOLD THE BOLTS, SAID LATCH ELEMENTS BEING ENGAGEABLE BY SAID BOLTS FOR HOLDING SAID BOLTS AS THE DOOR IS CLOSED, SAID BOLTS BEING DISENGAGED FROM SAID LATCH ELEMENTS WHEN SAID LATCH ELEMENTS ARE IN LATCHING POSITION BY RETRACTING THE BOLTS TOWARD THE DOOR HEAD EDGE. 